Yup, no benefits until there is a baby Unless you are already entitled. Centrelink don't pay for a baby in utero

I would also say on the forms (when bub is born and you get them) that you are de-facto, and from there on in any benefit you receive will be based on your combined income. If you say you are separated then to get any parenting payment from Centrelink you have to go through Child Support and if you aren't really separated then that's a load of hassle you don't need!! Plus if you get busted you will be in trouble

You'll get some Family Tax Benefit for sure If you are going to be living with your MIL then that will be a huge money saver too for not paying rent as such.

GL and Congrats